Writing on the Newsmax website, Reagan described director Lee Daniels’ depiction of Ronald as “a bunch of lies”, pointing out that his father signed the law that created Martin Luther King Day and promoted the real-life White House staff member at the centre of the film to maître d’hôtel.

“It’s appalling to me that someone is trying to imply my father was a racist,” wrote Michael. “He and Nancy and the rest of the Reagan family treated Mr Allen with the utmost respect. It was Nancy Reagan who invited the butler to dinner – not to work but as guest. And it was my father who promoted Mr Allen to maître d’hôtel.

“The real story of the White House butler doesn’t imply racism at all. It’s simply Hollywood liberals wanting to believe something about my father that was never there.”

The former conservative talk show host – the adopted son of Reagan and first wife, Jane Wyman – said his father’s support for lifting sanctions on South Africa’s apartheid regime in the 1980s had “nothing to do with the narrow issue of race”, adding: “It had to do with the geopolitics of the cold war. But facts don’t matter to Hollywood’s creative propagandists. Truth is too complicated and not dramatic enough for scriptwriters, who think in minute terms, not the big picture, when it comes to a conservative.”

Ronald Reagan is portrayed by Alan Rickman in The Butler. Oprah Winfrey plays Gaines’s wife, Gloria, with Britain’s David Oyelowo as his civil-rights activist son, Louis. Robin Williams, Melissa Leo, James Marsden, Minka Kelly, John Cusack and Jane Fonda appear as the various other US presidents and first ladies whom Gaines meets along the way.

Michael Reagan has not always had such kind words for his father, who sent him off to boarding school at the age of six. In a 1988 biography he revealed that the president failed to recognise his own son during a visit to the exclusive Judson prep school outside Scottsdale, Arizona, for a graduation ceremony.

President Obama revealed earlier this week that he was moved to tears while viewing Daniels’ film, which is currently riding high at the US box office. “I teared up thinking about not just the butlers who worked here in the White House, but an entire generation of people who were talented and skilled. But because of Jim Crow and because of discrimination, there was only so far they could go,” he said.